Influence of extraoral scan body design on accuracy of scans recorded using four intraoral and one desktop scanner, with and without AI features: An In Vitro Study.

Abstract

Objectives: The aim of this in vitro study was to evaluate the impact of extraoral scan body (ESB) design on the scanning accuracy of a digitized facebow fork along with the attached ESB, using four intraoral scanners (IOS) and one extraoral desktop scanner (EOS), with and without the assistance of the available integrated artificial intelligence (AI) tools.

Methods: One facebow fork and 4 ESBs were additively manufactured. The ESB designs included three different geometries: cube, ball, and rectangle. Each design was fabricated using a gray-colored resin. Four 6-mm-diameter gauge balls were affixed to the facebow fork, and five were attached to each ESB. A printed maxillary cast was initially secured to the facebow fork using an interocclusal registration material and subsequently detached. Each ESB was individually attached to the facebow fork and digitized 10 times using each of the four IOS devices (Aoralscan 3, i700, Primescan, and Trios 5) as well as one laboratory scanner (T710). For the Aoralscan 3, i700, and Trios 5 devices, scans were conducted both with and without the use of AI-assisted scanning features. To establish a reference dataset, each assembled ESB was also scanned using an industrial-grade scanner (Atos Q 3D 12M). Accuracy was assessed by comparing the experimental scans to the reference scan, measuring both linear distances between the gauge balls and angular deviations of the planes defined between the facebow fork and each ESB. Trueness was statistically analyzed using one-way ANOVA and Tukey's pairwise multiple comparison tests (α = .05). Precision was evaluated using Levene's test for equality of variances, followed by pairwise comparisons using the Wilcoxon rank-sum test with continuity correction (α = .05).

Results: There was a significant difference in both trueness and precision among the evaluated ESBs, when scanned using the evaluated IOSs (P<.05). The laboratory scanner demonstrated higher overall accuracy compared to the IOSs (P<.05), remained consistent regardless of the ESB's design and color (P>.05). The AI-assisted tool provided by the Trios 5 improved the trueness of extraoral ESB digitization.

Conclusions: The type of IOS affected the accuracy of the digitized ESB. The design and the color of the ESB impacted scanning accuracy, only when IOSs were used. ESBs with larger dimensions and more complex geometries posed significant challenges for certain IOSs, making in some cases their digitization impossible. The effectiveness of integrated AI-assisted scanning tools varied among devices, producing either beneficial or adverse effects depending on the specific IOS system.

Clinical significance: ESBs can assist in both the superimposition and orientation of the virtual patient representation. However, as the size and geometric complexity of these devices increase, the use of a laboratory scanner is recommended to ensure accurate virtual patient representation. Clinicians should also consider the specific capabilities and limitations of the intraoral scanner being used, as AI-assisted scanning tools integrated into IOS systems may either enhance or compromise the accuracy of the digitization process.